Abstract
BACKGROUND: Virtual reality (VR) enables objective and accurate measurement of behavior in ecologically valid and safe environments, while controlling the delivery of stimuli and maintaining standardized measurement protocols. Despite this potential, studies that compare virtual and real-world performance of complex daily activities are scarce. This study aimed to compare cognitive strategies and gait characteristics of young and older healthy adults as they engaged in a complex task while navigating in a real shopping mall and a high-fidelity virtual replica of the mall. METHODS: Seventeen older adults (mean (SD) age = 71.2 (5.6) years, 64% males) and 17 young adults (26.7 (3.7) years, 35% males) participated. In two separate sessions they performed the Multiple Errands Test (MET) in a real-world mall or the Virtual MET (VMET) in the virtual environment. The real-world environment was a small shopping area and the virtual environment was created within the CAREN™ (Computer Assisted Rehabilitation Environment) Integrated Reality System. The performance of the task was assessed using motor and physiological measures (gait parameters and heart rate), MET or VMET time and score, and navigation efficiency (cognitive performance and strategy). Between (age groups) and within (environment) differences were analyzed with ANOVA repeated measures. RESULTS: There were no significant age effects for any of the gait parameters but there were significant environment effects such that both age groups walked faster (F((1,32)) = 154.96, p < 0.0001) with higher step lengths (F((1,32)) = 86.36, p < 0.0001), had lower spatial and temporal gait variability (F((1,32)) = 95.71-36.06, p < 0.0001) and lower heart rate (F((1,32)) = 13.40, p < 0.01) in the real-world. There were significant age effects for MET/VMET scores (F((1,32)) = 19.77, p < 0.0001) and total time (F((1,32)) = 11.74, p < 0.05) indicating better performance of the younger group, and a significant environment effect for navigation efficiency (F((1,32)) = 7.6, p < 0.01) that was more efficient in the virtual environment. CONCLUSIONS: This comprehensive, ecological approach in the measurement of performance during tasks reminiscent of complex life situations showed the strengths of using virtual environments in assessing cognitive aspects and limitations of assessing motor aspects of performance. Difficulties by older adults were apparent mainly in the cognitive aspects indicating a need to evaluate them during complex task performance.